Granted, demand will affect the volume of stuff they have to transport, but the price of the product really shouldn't matter much. But stock prices are not rational beings.

Anyway, I smell an opportunity in coal. Many investors seem to be avoiding it -- all the more reason to look at it. In the coal MLP space, Natural Resource Partners, LP (NYSE: NRP) is a compelling idea. The company owns and manages domestic coal reserves in Appalachia, the Illinois Basin and the Powder River Basin. Rather than owning and operating coal mines and producing its own coal, Natural Resource Partners leases its properties and reserves to mine operators in return for royalty payments. All leases are long-term, and the company has more than 2 billion tons of reserves.

Units are trading at around $26.50, which is a 25% discount to their 52-week high and are yielding 8.3% (the term for an ownership stake in MLPs is "units," rather than "shares"). The attraction to Natural Resource Partners is the lack of exposure to the direct risks of mine operation (remember Massey Energy?). The income stream also appears more stable, thanks to its royalty collection model.

Natural gas
StreetAuthority's energy expert Nathan Slaughter, however, is a much bigger fan of natural gas. Natural gas has a much cleaner perception and is just as abundant if not more so than coal. The problem with natty gas is that the huge supply has kept prices in the basement. Also as an industry group, it remains very fragmented. Many natural-gas distributors and producers are still independent. This makes it difficult to get the kind of true political traction required to gain any significant policy shift.

But that doesn't mean there's not money to be made.

And while coal may be the stepchild of the energy world, natural gas is the consistently underachieving middle child. Natural-gas prices have floundered in a sub-$5/cubic foot channel for the better part of a year. At the same time, natural gas extraction technology continues to become more and more cost efficient, allowing producers to pull more and more of it out of the ground cheaply.

Supply isn't a problem. Demand is. Natural gas demand is anemic at best: yet another energy head scratcher. Natty gas is clean, cheap and abundant. Real abundant. We should be using it to power our homes, keep us warm and drive our cars. (In fact, Nathan thinks this may happen soon enough.)

One stock I like is Niska Gas Storage Partners (NYSE: NKA). Niska is the largest independent owner and operator of natural-gas storage in North America. In total, the company has about 185.5 billion cubic feet of storage capacity. They're only using 55% of that.

Needless to say, the stock's fundamentals aren't the greatest. But the story behind owning this stock is the valuation. Units trade around $9.37 and yield better than 14%. They're also priced at a 27% discount to their book value.